EXPERIMENTAL AND THEORETICAL STUDIES OF CRITICAL DEFORMATIONS GLUED WOOD

Abstract

A detailed analysis of literature sources on the performance of glued wood under various types of load was carried out. It was established that there are no experimental and theoretical studies of critical deformations of glued wood at standard humidity.The methodology of experimental studies of laminated wood of deciduous and coniferous species by axial compression along the fibers under a strict regime of tests on modern testing equipment is given. The following types of wood were subjected to experimental research: birch, alder, ash, larch, pine, spruce. The moisture content of the wood at the time of testing was 12%. Experimental studies were carried out on a modern STM-100 testing machine. The rate of deformation was 1.5 mm/min. A total of 36 samples were tested. Complete (valid) deformation diagrams "stress σc – relative deformations uc" of glued hardwood and softwood were constructed. The critical relative deformations of such materials were determined experimentally andtheoretically. A formula for determining the critical relative deformations of glued wood is proposed, which includes elastic and plastic components. It was established that for the critical relative deformations, which are determined theoretically, there is a characteristic insignificant increase and decrease of the values in comparison with solid wood with a moisture content of 12% and an age of 60 years. In the same way, a change in the deformations of the elastic component of the function is observed, while the plastic component significantly increases by 3.9–41.3%. A statistical analysis of the conducted research is presented.